This application is designed to study the free-radical mechanisms underlying "non-thermal" microwave radiation induced damage to ocular structures. The association of free-radicals in ocular tissues, following acute/chronic exposures to low levels of microwave radiation, with specific tissue damage (corneal endothelium and vascular permeability) will be evaluated in vivo (rabbit model). The occurrence of free-radicals will be monitored by electron spin resonance (ESR) employing spin-trapping and spinstabilization techniques. Model membrane systems will be employed to study the interaction of various sub-cellular components (melanin, ascorbate, Shiff's bases) with microwave induced free-radicals, and to evaluate their roles in formation/detoxification mechanisms. The subsequent effect of these free-radical species can then be evaluated by correlating changes in membrane characteristics (membrane fluidity) with protein function (ATPase activity). The eye represents an incredibly complex organ, with a multitude of highly differential tissues. Thus, tissue specific exposure techniques employing a variety of cell lines will be employed to demonstrate which tissues are most critical in the microwave induction of free-radical species. In addition, possible interactions between tissues will be possible by employing co-culture techniques. Finally, an attempt to demonstrate a causal relationship between formation of free-radical species in the eye and subsequent tissue damage will be conducted using free-radical generating systems in combination with free-radical scavenging systems. It is felt that this unique demonstration of free-radical induced damage in ocular tissue by non-thermal levels of microwave radiation provides useful mechanistic information for establishing safe environmental and occupational exposure levels for some sources of electro-magnetic radiation.